I've used this one, and love it. The edge of the glass is rounded off, and you can't even tell it's there--by look or feel. Other brands I've used had squared edge and I don't care for it.

Comes in a pack of three for only $8. https://www.amazon.com/dp/B01LW1U5XX/ref=cm_sw_r_cp_apa_111SzbRYNH8MH

Samsung Gear S3 Screen Protector [3 Pack], OMOTON Full-Coverage Tempered Glass Screen Protector for Samsung Gear S3 with [9H Hardness] [Crystal Clear] [Scratch Resist] [Bubble Free Installation] https://www.amazon.com/dp/B01LW1U5XX/ref=cm_sw_r_cp_apa_S-0SzbPBVSAH3

I bought these and they are great. I wanted to use it for a trip to Florida back in June (to protect the screen from sand) and then was going to take it off when I got home. Well it's still on. It looks like new.